The invention relates generally to fiber optic sensing devices, and more particularly, to a fiber optic sensing device for detecting multiple parameters of a device operating in an environment, for example, in a turbomachinery environment including brush sealing system, a rotor thrust bearing, or the like.
Various sensing devices are known and are generally in use. For example, thermocouples are used for measuring the temperature in components of a device, such as exhaust systems, combustors, turbomachineries, and so forth. In certain other instances, sensing systems are employed to detect physical parameters such as, strain or temperature in an infrastructure. However, such conventional sensing devices are limited by the operational conditions in which they may be employed. For example, conventional sensing devices are often limited to relatively mild temperature conditions and, as such, limited operational temperature ranges.
In one example, thermocouples are provided proximate to brush seals located in test rigs. The data collected during testing period is then extrapolated to turbo machines operating in real time conditions. In certain other instances, proximity probe data or accelerometer data is collected during a rotor's life cycle to identify rotor growth and vibration problems. However, it was difficult to extract exact temperature data at the interface between the seal and the rotor. Moreover, it was also difficult to sense induced strain at the rotor-seal interface.
Conventionally, the measurement of thrust on rotor bearing of rotary machine has been accomplished by the application of electrical resistance strain gages to a bearing housing or bearing race. Unfortunately, this electrical resistance strain gage technology of the existing art encounters several problems and limitations. One problem encountered is that the strain gage indicated output is dependent upon its temperature environment at any thrust load, thus inducing errors into the measurement. In addition, the strain gages are subject to mechanical fatigue failure and, thus, loss of signal. Another problem is that the strain gages are subject to electrical magnetic interference or other induced electrical noise, thus inducing errors into the thrust load measurement. Yet another problem encountered is that the strain gages are not an absolute measurement, as they require an electrical tare balance and other thermal compensations. Also, the electrical resistance-based strain gage possesses a calibration constant known as the gage factor, which varies as a function of temperature and can produce an error in the indicated thrust measurement. The conventional technique also does not effectively address the issues relating to mitigation of thrust load on the bearings.
There is a need for a device and method that effectively extracts the temperature and strain data of a device operating in an environment. There is also a need of a technique for accurate measurement and control of thrust load on a rotor bearing.